1. Field of the Invention
The present invention relates to a camera having a built-in tilt mechanism for bringing at least two subjects into focus and a camera having a built-in flashing device capable of distributing light to the two subjects optimally.
2. Description of the Related Art
When multiple main subjects are present within a photographic angle of field, two methods have been adopted to take photographs in which at least two subjects existent at different distances from a camera are in focus.
The first method has been disclosed in Japanese Patent Laid-Open No. 62-52538, wherein an f-number is optimized and thus a focus is adjusted to provide a subject field depth that is deep enough to include multiple subjects. The second method is based on a law of shine-proof (to be described later). According to the law of shine-proof, when a photographic optical system is tilted to incline subjects to be imaged with respect to a film surface, multiple subjects at different distances will come into focus. This method is popular among, for example, skilled people who use an exchange lens in combination with a 35-mm single-lens reflex camera having a tilt mechanism.
Various methods based on the law of shine-proof have been proposed to enable tilt photography not using any sophisticated technology. For instance, in Japanese Patent Laid-Open No. 2-79808 the present applicant has proposed and Japanese Patent Laid-Open No. 2-55212 have disclosed tilt photography using a multi-point distance measuring mechanism that measures distances to subjects in multiple distance measurement domains to calculate a quantity of tilt, then tilts the photographic optical system according to the calculated quantity of tilt. Then, these methods imply that tilt photography can easily be implemented in lens-shutter type cameras.
However, the first method, which is dependent on a subject field depth has a problem that usable situations are limited because a subject field depth becomes insufficient depending on brightness of a subject or a difference between distances to subjects. The first method has proved effective only on limited occasions.
The second method using the tilt mechanism has an intended advantage. However, the existing multi-point distance measuring mechanism automatically measures distances to multiple main subjects 154 and 155 existent in multiple predetermined distance measurement areas 151, 152, and 153 within a photographic screen when release is done. The multiple main subjects 154 and 155 are not always positioned in the distance measurement areas 151, 152, and 153 (See FIG. 78). Therefore, only when multiple subjects are positioned in the distance measurement areas, an image in which all the subjects are in focus cannot be produced. Therefore, the method is usable on strictly restricted occasions. Consequently, a lens-shutter type automatic focusing camera having a tilt mechanism has not made its debut.
On the other hand, when a subject illuminance is lower than a certain level, a strobe has been employed in the past. Strobe lighting from a camera to subjects is designed to be uniform within a photographic angle of view. The lighting characteristic of a conventional strobe will be described below.
FIG. 83 plots the lighting characteristic in the longitudinal direction of a screen of a strobe conventionally employed. Herein, the x axis represents right and left angles with respect to the optical axis of a photographic lens, and the y axis represents a quantity of flashlight the strobe produces. The lighting characteristic of FIG. 83 applies to a normal full-size film camera having a photographic lens with a focal distance of 35 mm, which is uniform at about 27.degree. or less on each side of an angle of view.
In actual strobe photography, no problem occurs when subjects 161 to 163 reside at the same distance h1 from a camera 160 as shown in FIG. 84. When main subjects 164 to 166 reside at different distances h1, h2, and h3 within an angle of view, since a strobe lighting pattern is uniform within a photographic angle of view, only one point among subjects can be exposed to light correctly.
When a condition closest to a natural scene must be created, multiple strobes have been used to radiate flashes or bounce photography has been carried out.
Alternatively, a means for using a single strobe and changing lighting in an angle of view according to a type of subject has been disclosed in Japanese Examined Utility Model Publication No. 59-28416 or Japanese Examined Patent Publication No. 61-19021. In these means, a liquid crystal plate capable of influencing part of a strobe light transmission range is placed in the front of a flashing unit having a uniform pattern. Then, when release is done, before main flashing is executed, infrared light is projected to the screen to check if a subject resides nearby. If a subject is present, the liquid crystal plate is driven to attenuate the strobe light in the area corresponding to the subject, and thus lighting is varied.
When multiple strobes are employed or the foregoing means enabling bounce photography is used, a large-sized and sophisticated strobe results. In addition, a photographer must find an optimal setting for all subjects, and, therefore, needs advanced skill. Therefore, only skilled people can enjoy photography using cameras having such strobes, but ordinary users find it very difficult to use the cameras.
A means for varying lighting using a liquid crystal member placed in the front of a flashing unit has been disclosed in Japanese Examined Utility Model Publication No. 59-28416. Using this means, a liquid crystal member and a liquid crystal control having no direct relation to a strobe must be installed in a camera. Furthermore, the means shields effective rays using liquid crystals to provide various lighting characteristics, which, therefore, is subject to a large loss due to diffusion and heat dissipation. Even if an intended lighting characteristic is yielded, a quantity of flashlight from the strobe diminishes greatly.
Moreover, the flashing unit is not a point light source. Even if the front of the flashing unit is partly shielded, overall lighting is hardly reduced. Thus, a variable range of a lighting pattern is strictly limited.
Then, the present applicant has submitted Japanese Patent Application No. 2-409240 and proposed a double-flash type "variable lighting strobe" characterized by two flashing units having heteromorphic lighting patterns that are symmetric with respect to the photographic optical axis. Then, the flashing units are controlled in such a way that their quantities of light are varied to provide various lighting patterns.
Proposed in Japanese Patent Application No. 2-408198 is a strobe in which lighting control for the variable lighting strobe is automated depending on multi-point automatic focusing (hereafter, AF) information.
Lighting variation proposed in Japanese Patent Application No. 2-409240 is achieved manually. This has proved helpful for experienced people because it allows them to take photographs as they imagine, but has been difficult for newcomers to use.
A means using a technology based on multi-point AF and proposed in the Japanese Patent Application No. 2-408198 is friendly to newcomers. However, when three-point AF is employed, if main subjects are away from a distance measurement position, intended results are unavailable. That is to say, as shown in FIG. 77, when subjects 154 and 155 agree with second and third distance measurement frames 152 and 153, no problem occurs. However, when photography is attempted in a photographic scene in which the subjects 154 and 155 disagree with the distance measurement frames 152 and 153, distance measurement is disabled.